1. Field of the Invention
The present invention relates to a mobile communication system and a method for implementing a Multi-Input Multi-Output (MIMO) transmission method in the mobile communication system. More particularly, the present invention relates to a method for implementing an MIMO transmission in a mobile communication system by configuring a transmitter, a transmitter antenna, and a receiver antenna into a single device.
2. Description of the Related Art
A Multi-Input Multi-Output (MIMO) transmission method refers to a smart antenna technique for increasing a wireless communication capacity. Specifically, MIMO transmission methods use multiple antennas on a base station and a terminal. Further, according to MIMI transmission methods, wireless communication capacity is increased in proportion to the number of antennas employed. Generally, in the MIMO transmission method, the base station indicates a transmission terminal and the terminal indicates a receiver terminal. When M number of antennas are installed in the base station and N number of antennas are installed in the terminal in order to implement an MIMO technology, an average transmission capacity of data transmission is increased by min(M, N).
In a mobile communication system, removal of spatial interference is important in order to allow effective dynamic frequency allocation between cells. Also, a spatial interference processing between Access Points (APs) is important due to an increase in a number of APs communicating in mobile communication systems. A method for spatial interference processing may include a method of dynamically or position adaptively decreasing a frequency recycle ratio. However, such method causes a loss of a frequency resource. When using the MIMO transmission method for the spatial interference processing, data can be transmitted without frequency loss.
FIG. 1 illustrates a configuration of a base station for transmitting data in a communication system using a MIMO transmission method according to the related art. Herein, it is assumed that the base station uses the MIMO transmission method to transmit and receive a signal through two antennas.
Referring to FIG. 1, a signal transmission path in the base station is described.
A signal processing unit 110 generates signals based on data to be transmitted through each antenna and simultaneously transmits the signals to respective filters 113, 123, 133, and 143. First, a signal processing path through an antenna 1, 119, will be described.
A signal corresponding to data to be transmitted is passed to the first filter 113 through the signal processing unit 110. The first filter 113 transmits a signal to be transmitted to a first pulse amplitude modulator 115. The first pulse amplitude modulator 115 amplifies the signal at a maximum power so that, when the signal is emitted from the antenna, an electromagnetic wave corresponding to the signal may reach a desired destination. A duplexer 117 passes only a signal to be transmitted through the antenna such that the signal is emitted through the antenna 1, 119.
A path in which a signal transmitted from a terminal is received by the base station through the antenna 1, 119, is described. A signal received through the antenna 1, 119, passes through the first duplexer 117 to be transmitted to a low noise amplifier 120. A signal amplified by the low noise amplifier 120 is filtered by the filter 123 and is transmitted to the signal processing unit 110.
A signal transmitting and receiving path through an antenna 2, 139, is configured substantially the same as a signal transmitting and receiving path through the antenna 1, 119. However, a difference exists in the filters 113, 123, 133, and 143, the pulse amplitude modulators 115 and 135, the duplexers 117 and 137, and the low noise amplifiers 120 and 140 of the base station that are respectively provided for each antenna and for each transmission and receiving means.
The signal processing unit 110 process signals received through the antenna 1, 119, and the antenna 2, 139, to generate one datum.
FIG. 2 illustrates a method of transmitting a signal in a communication system using a MIMO transmission method according to the related art.
Referring to FIG. 2, a signal transmitted through a transmitter antenna 1, 210a, is transmitted to a receiver antenna 1, 230a and to a receiver antenna 2, 230b. Also, a signal transmitted through a transmitter antenna 2, 210b, is transmitted to the receiver antenna 1, 230a, and to the receiver antenna 2, 230b. 
However, in base stations using MIMI transmission methods according to the related art, respective base stations and terminals need to be configured with a plurality of antennas, thus being subject to spatial limitations. Also, configuring the respective base stations and terminals to include the plurality of the antennas incurs a high cost.
Therefore, a need exists for a system and method for implementing an MIMO transmission in a mobile communication system by configuring a transmitter, a transmitter antenna, and a receiver antenna into a single device.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention.